Differential steer, that is, the ability to steer a machine, such as a tractor or the like, by supplying power to a drive wheel or track on one side of the machine, while applying a brake and/or supplying lesser or no power to a drive wheel or track on the opposite side of the tractor, is a well known operational feature used in both wheeled and tracked machines such as bulldozers and farm tractors. Similarly, a PTO unit, typically comprised of a rotatably powered auxiliary shaft having an output member to which implements or devices such as pumps, augers, mowers, cutters, and the like can be coupled to receive power, is also a well known feature. A PTO unit is often provided in association with a drawbar of a hitch for attaching the implement or device to be powered to the machine for towing purposes, the output end of the PTO unit typically being located at a known fore to aft distance and height above the drawbar to standardize attachment. For tractors and other machines that do not utilize differential steer, and also larger machines that do utilize differential steer, such as large agricultural tractors, surface mining equipment and the like, positioning the PTO output at the desired location and routing the PTO shaft or other power transmission member thereto is not problematic, as ample space for passage of the shaft or other member is typically available, due either to the absence of a differential steer mechanism, or to the larger size of the machine and correspondingly large spaces available for the passage of PTO shafts and the like. For smaller machines, on the other hand, particularly small tracked or wheeled tractors for agricultural and construction purposes utilizing differential steer, placement of the PTO output and routing power transmission equipment thereto, particularly a PTO shaft, can be a problem, due to the presence of a differential steer mechanism, and/or the smaller spaces around and through the final drive mechanism or mechanisms available for passage of the PTO shaft. Reference, Smith, U.S. Pat. No. 4,335,796, issued Jun. 22, 1982 to Deere & Company, which discloses a PTO rear mounting arrangement wherein the PTO output is desirably positioned, but which requires mounting the PTO shaft atop the transverse axle casing containing the drive differential, and locating the PTO transmission rearward thereof.
An alternative possible location for passage of the PTO shaft is beneath the final drive axle casing. However, this location can be disadvantageous if it results in sufficiently small ground clearance such that the shaft or part of the PTO assembly can strike and damage the tops of crops over which it passes. This problem may arise, for instance, when the PTO shaft is located on or in the vicinity of the tractor fore to aft centerline and the crops are planted in rows spaced 15 inches apart such that a crop row is located under or in close proximity to the fore to aft centerline as the tractor moves along the rows.
Accordingly, the present invention is directed to overcoming one or more of the problems as set forth above.